Gaseous drilling fluids



United States Patent 3,277,971 GASEOUS DRILLING FLUIDS Lester Roy Dawson, Houston, Tex., assignor to Dril-Kem, Inc., Houston, Tex., a corporation of Texas No Drawing. Filed Dec. 20, 1962, Ser. No. 245,989 2 Claims. (Cl. 175--71) This invention pertains to the drilling of wells wherein non-liquid drilling fluids are used during drilling. In greater particularity, the invention pertains to the lubrication of the drill stem and drill bit in connection with the drilling wells wherein a gaseous drilling fluid is employed to remove the drilled cuttings from the hole as drilling proceeds.

A principal object of the invention is to provide lubricated dry drilling procedures.

A further object of the invention is to provide lubricated drilling in wells wherein gaseous drilling fluid is employed, wherein molybdenum disulfide is incorporated in the gaseous drilling fluid as a lubricant to assist in reducing drill stem torque and to prevent sticking or hanging of the drill stem in the hole as drilling proceeds.

In the drilling of wells wherein gaseous drilling fluids are employed, problems exist which are not present in the case of the drilling of wells wherein liquid or slurry drilling fluids are employed. In the case of the latter type of wells, the presence of a liquid drilling fluid provides inherently at least some lubrication of the drill string and drill bit while drilling is taking place, so that stuck drill pipe and like problems do not exist to such a large extent as in the case of wells drilled with a substantially dry gaseous drilling fluid. The use of the expression dry gaseous drilling fluid herein means that there is no separate liquid drilling fluid present or circulating through the well.

Various lubricating materials have been incorporated in liquid drilling fluids, but to the present time, no lubricants have been effectively provided in the case of dry fluid well drilling. According to this invention, it has been discovered that molybdenum disulfide has beneficial effects in the drilling of wells in that it provides lubrication of the drill string and of the drill bit to such a degree that drilling torque is largely eliminated or at least greatly reduced, and it has been further found that use of compositions or formulations including molybdenum disulfide have resulted in the release of stuck drill strings, and the like, in wells.

Other objects and advantages of the invention will appear from the following description of preferred embodiments of the invention.

Describing the invention in detail, the use of molybdenum disulfide, and the formulation of compositions containing molybdenum disulfide, have been achieved which greatly enhance the drilling of dry well fluid wells. When such wells are drilled, the gaseous drilling fluid is circulated into the well, usually through the drill string, to which it is introduced at the drilling rig, the fluid flowing through the drill string to the bottom of the well and out into the annulus of the Well. Usually the drilling fluid is introduced to the annulus of the well at the drill bit in such a manner that the drilling cuttings are effectively carried away from the drill bit and removed from the well so that the cuttings do not accumulate in the bottom of the hole as it is drilled.

Any apparatus suitable for introduction of the molybdenum disulfide or formulations thereof to the circulating gaseous drilling fluid may be employed.

Powdered dry molybdenum disulfide may be introduced to the drilling fluid at the top of the well either alone or in the form of formulations combined with other mate rials. It has been found that molybdenum disulfide introduced alone is effective, but even more effective are formulations of molybdenum disulfide with certain other materials. The following are exemplary formulations which have been effectively employed.

Component: Percentage (by weight) Molybdenum disulfide 3 Calcium stearate 45 Calcium hydroxide 50 Glycol 2 Molybdenum disulfide 1.5 Calcium stearate 45.5 Calcium hydroxide 51.0 Glycol 2.0

(III) Molybdenum disulfide 15 Calcium stearate 39 Calcium hydroxide 44 Glycol 2 The listed drilling compositions or formulations have been effectively employed, but these are exemplary and other compositions may effectively be employed. It has been found that molybdenum disulfide in these formulations from about one-half percent upward to fifteen or twenty percent is effective. The calcium stearate may be varied from about thirty-five percent to about fifty percent of the composition. The glycol is usually employed as two percent of the mixture, to assure effective mixing of the formulation and for other purposes. Calcium hydroxide makes up the balance of the formulation, in this type of formulation. Other metallic soaps than calcium stearate may be employed.

As an example of the use of this type of formulation, in a well located in West Texas, the well was being drilled to above 10,000 feet. Approximately 7,000 feet of drill string was, because of separation of the drill string, dropped about 3,000 feet in the drilled hole. Because of the torque imposed on the drill string at the time of the drill string separation, the 7,000 feet of drill string became corkscrewed and stuck in the hole and had to be retrieved by fishing. The fishing procedures were ineffective, as the twisted condition of the drill string made it impossible to remove it from the hole by conventional fishing procedures. The well was scheduled to become abandoned by the operator because of the stuck drill pipe in the hole. Five hundred pounds of the composition indicated as Formulation I, above, was introduced to the circulating gaseous drilling fluid. After a few minutes, the fishing was resumed in an effort to remove the stuck drill pipe. It was found that the drill pipe was then easily removed from the hole, the molybdenum disulfide formulation effectively lubricating and unsticking the pipe in the hole so that it could be readily removed in spite of its previously corkscrewed and stuck condition therein, after having been dropped in the hole about 3,000 feet.

During ordinary drilling, where the drill string has not become stuck in the hole, the load on the drilling apparatus at the top of the hole has been found substantially equal to that due to the weight of the drill string itself, the friction of the drill string in the hole being substantially reduced to zero. This reduction in drilling torque is effective in making the drilling much more economical than heretofore.

The molybdenum disulfide and molybdenum disulfide formulations herein indicated are useful both during drilling and in the case of stuck pipe in the hole. During drilling, the reduced torque makes the drilling more economical and imposes less strain on the drilling equipment, so that wear on the drill string is reduced. The use of such materials results in simple lubrication of down-hole bits and tools. Extreme pressure lubrication of downhole bits and tools results. Reduction of drag in tight or crooked holes has been found to result. Uses of Formulations IIII, above, and other like formulations, have been found to inhibit corrosion in the hole. The formulations assist in water-proofing of the formation. Use of the materials results in water-proofing of cuttings to prevent balling thereof in the hole, which hampers the drilling of the hole. It has been found that use of the material indicated greatly increases :penetration rates, so that drilling of the hole is speeded up. Further, it has been found that bit life is greatly improved, so that removal of the drill string to replace the bit need be done only at longer intervals, resulting in still further drilling economies.

[While preferred embodiments of the invention have been described, many medications thereof may be made by a person skilled in the art without departing from the spirit of the invention, and it is intended to protect by Letters Patent all forms of the invention falling within the scope of the following claims.

I claim: r

1. Formulations for addition to gaseous drilling fluids, comprising about 0.5% (by Weight) to about 20% (by weight) molybdenum disulfide, about 35% (by weight) References Cited by the Examiner UNITED STATES PATENTS 2,805,991 9/1957 Tailleur 2528.5 2,814,464 11/1957 Pike et a1. 175337 2,999,551 9/1961 Murphy 17568 3,071,543 1/1963 McGee 252-495 3,126,970 3/1964 Rygg 16644 X OTHER REFERENCES Stormont, D. H.: Air Used for Drilling and Pumping in Sharon Field in West Texas, in the Oil and Gas Journal, August 17, 1939, page 52.

CHARLES E. OCONNELL, Primary Examiner.

T. A. ZALENSKI, S. I. NOVOSAD, Assistant Examiners. 

1. FORMULATIONS FOR ADDITION TO GASEOUS DRILLING FLUIDS, COMPRISING ABOUT 0.5% (BY WEIGHT) TO ABOUT 20% (BY WEIGHT) MOLYBDENUM DISULFIDE, ABOUT 35% (BY WEIGHT) TO ABOUT 50% (BY WEIGHT) CALCIUM STEARATE, ABOUT 2% (BY WEIGHT) GLYCOL, AND THE BALANCE CALCIUM HYDROXIDE.
 2. IN A METHOD OF DRILLING A WELL WHEREIN A GASEOUS FLUID IS EMPLOYED TO REMOVE CUTTINGS AND THE LIKE FROM THE HOLE BEING DRILLED, THE IMPROVEMENT COMPRISING THE STEP OF CIRCULATING THROUGH THE DRILL STRING AND AROUND THE DRILL CUTTING SURFACES IN THE HOLE A DRY GAS CONTAINING DISTRIBUTED PARTICULATE MOLYBDENUM DISULPHIDE AND SELECTED PROPORTIONS OF CALCIUM STEARATE, CALCIUM HYDROXIDE AND GLYCOL. 